"For years now, Linux has been a black sheep standing in the shadow of Apple and Microsoft. Despite having a fervent and enthusiastic following, the operating system hasn't been able to grab a sizable share of the computing market and has instead been content to subsist on the customers that come away dissatisfied with the mainstream competition. But that may be about to change. With the release of Microsoft Windows 8 on the horizon, some are saying Linux may have a great opportunity to steal a significant share of the market away from Microsoft, allowing it to finally take the helm as a major operating system service provider." This has to stop, and the only reason I'm linking to this nonsense is to make this very clear: Linux will not magically conquer the desktop or even make any significant gains because of Windows 8. People who don't like Windows 8 (Vista) will continue to use Windows 7 (Windows XP). This is getting so tiring. And does it even matter? Linux is winning big time in the mobile space, server space, and countless other spaces. The desktop is and always has been irrelevant to Linux.

Yeah, that particular setup the guy is trying to get is so very common. Hell most motherboards won't even support two video cards, let alone 3 of them!

By the way (and I would reply to his post, but apparently I don't have a Linux Mint account, but I'll create one just to respond to this guy, because I know the answer), the issue is with nVidia's driver not working with TwinView and any number of monitors that isn't even. So if he wanted 4 monitors it would work, but not with 3. Ran into this same issue on my work PC (though I have two video cards, and three monitors).

If he used the open source driver, it should work just fine.

Virtually all motherboards will support as many graphics cards as they have slots - GFX cards don't come only in PCIe x16 flavour, you know... (plus in many mobos at least some of the smaller PCIe slots are "open", to allow for usual large-slotted cards in them; any hypothetical loss of performance is irrelevant, certainly so in the typical ~desktop multi-mon usages)

BTW, my old multi-monitor setup had all kinds of weird glitches when trying out Linux on it, using exclusively OSS drivers... (hell, the cards didn't even really have, by then, any closed drivers compatible with contemporary distros - but they were supposedly the premier examples of good, long-maintained, polished OSS drivers)
Somehow no issues at all under Windows, despite using relatively outdated drivers (manufacturers of both GPUs used in that setup stopped supporting them also on Win by then)